Lubrication scavenge system

Abstract

A lubrication scavenge system for an engine bearing compartment or the like utilizing a gear pump with two or more independent inlets with separate flow paths through the pump. The inlets and flow paths are maintained separate from each other by the use of inlet and discharge seal arcs to avoid any fluid communication therebetween. The pump can operate to pump different fluids through each inlet with the fluid being either a gas or liquid or a mixture of both and with the pump continuing its pumping action when there is an instantaneous interchange in the fluid being pumped at each inlet as can occur when the engine bearing compartment is subjected to varying positive and negative gravity forces.

We claim: 
     
       1. A dual inlet gear pump operable in either a pumping mode or a metering mode for scavenging fluid from a pair of compartment outlets and wherein the fluid at said compartment outlets may alternate between air or oil or a mixture thereof comprising, a pump housing having a pair of inlet ports for association one with each of said compartment outlets and a single discharge port, a pair of separate fill slots in said housing communicating one with each of said inlet ports, said housing having a pair of generally cylindrical pump chambers, a pair of rotatable meshing gears in said pump chambers which separately rotate past an associated fill slot to carry fluid to the discharge port, portions of the walls of said pump chambers defining inlet and discharge seal arcs for each gear to preclude any direct fluid communication between the inlet ports and between the inlet ports and the discharge port, said inlet seal arcs extending between the leading edge of each fill slot and the intersection of said pump chambers and at least equal to the spacing between adjacent gear tooth tips and the discharge seal arcs being at least equal to the spacing between adjacent gear tooth tips and extending between the discharge port and the trailing edge of the fill slots, bearing means pressure loaded against the end faces of the gears, and a passage through said bearing means which communicates with only one of said inlet ports when the pump is used in a metering mode to provide said pressure loading without creating a flow path between the inlet ports. 
     
     
       2. A dual inlet gear pump as defined in claim 1 including inlet filling ramps for progressive filling of gear tooth spaces. 
     
     
       3. A dual inlet gear pump as defined in claim 1 including trapping relief grooves communicating the discharge port with the area in which the gears come into fully-meshed relation. 
     
     
       4. A lubrication scavenge system for engine bearing compartments which are subject to negative and positive gravity forces and which contain oil and air comprising, a gear pump operable in either a pumping mode or a metering mode, said gear pump having a housing with three generally cylindrical pump chambers, a plurality of rotatable gears positioned one in each of said pump chambers with a central gear in mesh with each of a pair of outer gears to define four flow paths for fluid captured between gear teeth and the walls of the pump chambers with two of said flow paths being defined by teeth of said central gear, said housing having two pairs of inlet ports associated with fill slots with a first pair supplying fluid to said central gear and one of the outer gears, the other pair of inlet ports supplying fluid to said central gear and the other of said outer gears, a first discharge port in said housing for receiving fluid flow from the gears supplied with fluid by one of said first pair of inlet ports and one of said other pair of inlet ports, a second discharge port for receiving fluid flow from the central gear and the other of the outer gears, means defining inlet seal arcs at least equal to the spacing between adjacent gear tooth tips between the leading edge of each inlet fill slot and the intersection of the pump chambers containing said central gear and said outer gears to prevent communication between said fill slots, means defining discharge seal arcs at least equal to the spacing between adjacent gear tooth tips between the discharge ports and the trailing edge of the inlet fill slots, bearing means pressure loaded against the end faces of said gears, and means for directing fluid pressure within the pump to said bearing means without creating a flow path between said inlet ports which, with the pump operable in a metering mode, consists of a single passage through said bearing means which communicates with only one of said four inlet ports. 
     
     
       5. A lubrication scavenge system as defined in claim 4 including inlet filling ramps for progressive filling of gear tooth spaces. 
     
     
       6. A lubrication scavenge system as defined in claim 5 including trapping relief grooves communicating the discharge ports with the area in which the gears come into fully-meshed relation.